1. Field of the Invention
The present invention relates to an optical unit that has an optical system including at least a reflecting optical element.
2. Description of the Related Art
Optical units for use in image display devices such as liquid crystal projectors, include the one shown in FIG. 3. This configuration is disclosed in Japanese Unexamined Patent Application Publication No. 2000-19634.
Illumination light from an illumination light source 103 is separated into each color beam of RGB by mirror groups 104, 105, 140 and 150 to 153, including dichroic mirrors 104 and 140, and is guided to liquid crystal panels 110 to 112. Each color image light modulated by the liquid crystal panels 110 to 112, is color-synthesized by a color synthesis prism 102 and is projected from a projecting lens 106 to a screen or the like which is not shown in the figure, thus forming a color image.
The optical path length of each color beam of RGB from the light source 103 to the projecting lens 106 is configured to be roughly equal to each other. Moreover, the above-noted mirror groups are all fixed and arranged inside an optical housing 101.
Additionally, other publications such as U.S. Pat. Nos. 5,651,599 and 5,676,442 and Japanese Examined Patent Application Publication No. 7-15537 also disclose the configuration of liquid crystal projectors. In any configuration, mirror groups (reflecting optical elements) are housed and held in an optical housing.
In order to efficiently use illumination light from the light source 103 in the above-noted configuration, it is necessary to roughly match the irradiation region of each color beam RGB to each image display element 110, 111 and 112, to a screen size of each image display element 110, 111 and 112.
Therefore, an irradiation region of illumination light to an image display element is conventionally positioned by adjusting the angle of reflecting mirrors and dichroic mirrors that are arranged in optical paths. An irradiation region of illumination light is adjusted by using a mirror adjusting mechanism disclosed in, for instance, Japanese Unexamined Patent Application Publication No. 11-281876.
However, in the above-noted configuration where a housing of an optical unit is formed in one body in a box-form and all the reflecting optical elements are housed and held inside the housing, the housing has to have greater volume than an optical system (providing spaces between the housing and the reflecting optical elements for dimensional tolerance) so as to secure a volume to arrange the reflecting optical elements, which are often arranged to surround a liquid crystal panel and color synthesizing prisms or the like. Accordingly, the optical unit becomes large, and an image display device having the optical unit hence becomes large.
Moreover, the inclinations of reflecting mirrors or dichroic mirrors are changed to relocate an irradiation region of illumination light in the conventional image display device, thus distorting the irradiation region and causing so-called trapezoidal distortion. Accordingly, an irradiation region of illumination does not match a screen size of an image display element and illumination becomes uneven, and it is difficult to ideally adjust an irradiation region.
An optical unit holding an optical system so as to form an optical path inside a housing according to a first aspect of the invention, has at least one reflecting optical element. At least one reflecting optical element is formed in one body with the housing.
An image display device according to a second aspect of the invention has:
the optical unit which has an illumination optical system to guide light from a light source to an image display element;
at least one image display element; and
a projection optical system to project image light from at least one image display element onto a face to be projected.
An optical unit holding an optical system so as to form an optical path inside a housing according to a third aspect of the invention, has:
at least one reflecting optical element. A face opposite a reflection face of the reflecting optical element is exposed to the outside of the housing.
An image display apparatus according to a fourth aspect of the invention has:
the optical unit which has an illumination optical system to guide light from a light source to an image display element;
at least one image display element; and
a projection optical system to project image light from at least one image display element onto a face to be projected.
In accordance with a fifth aspect of the present invention, there is provided an illumination adjustment method in an image display optical unit which has:
a first reflecting optical element having a curved surface to reflect illumination light from a light source;
a second reflecting optical element having a curved surface to reflect illumination light reflected at the first reflecting optical element;
a third reflecting optical element having a curved surface to reflect illumination light reflected at the second reflecting optical element, and to guide light to an image display element; and
a means to shift the first reflecting optical element and the third reflecting optical element relative to the second reflecting optical element. The means essentially prevents changes in a shape and brightness of an irradiation region of the illumination light on the image display element, having a step to adjust position of the irradiation region on the image display element herein by using the means.
In accordance with a sixth aspect of the present invention, there is provide an illumination adjustment method in an image display optical unit which has:
a first reflecting optical element having a curved surface to reflect illumination light from a light source;
a second reflecting optical element having a curved surface to reflect illumination light reflected at the first reflecting optical element;
a third reflecting optical element having a curved surface to reflect illumination light reflected at the second reflecting optical element, and to guide light to an image display element; and
a means to shift the first reflecting optical element and the third reflecting optical element relative to the second reflecting optical element. The means shifts the first reflecting optical element and the third reflecting optical element parallel to a direction which is orthogonal to a normal of a reflection face of the second reflecting optical element, having a step to adjust position of and the means positions the irradiation region on the image display element herein by using the means.
In accordance with a seventh aspect of the present invention, there provided is an illumination adjustment method in an image display optical unit which has:
a first reflecting optical element having a curved surface to reflect illumination light from a light source;
a second reflecting optical element having a curved surface to reflect illumination light reflected at the first reflecting optical element;
a third reflecting optical element having a curved surface to reflect illumination light reflected at the second reflecting optical element, and to guide light to an image display element; and
a means to shift the second reflecting optical element relative to the first reflecting optical element and the third reflecting optical element. The means essentially prevents changes in a shape and brightness of an irradiation region of the illumination light on the image display element, having a step to adjust position of the irradiation region on the image display element herein by using the means.
In accordance with an eighth aspect of the present invention, there is provided an illumination adjustment method in an image display optical unit which has:
a first reflecting optical element having a curved surface to reflect illumination light from a light source;
a second reflecting optical element having a curved surface to reflect illumination light reflected at the first reflecting optical element;
a third reflecting optical element having a curved surface to reflect illumination light reflected at the second reflecting optical element, and to guide light to an image display element; and
a means to shift the second reflecting optical element relative to the first reflecting optical element and the third reflecting optical element. The means shifts the second reflecting optical element parallel to a direction which is orthogonal to a normal of a reflection face of the second reflecting optical element, having a step to adjust position of the irradiation region on the image display element herein by using the means.
An image display optical unit according to a ninth aspect of the invention has:
a first reflecting optical element having a curved surface to reflect illumination light from a light source;
a second reflecting optical element having a curved surface to reflect illumination light reflected at the first reflecting optical element;
a third reflecting optical element having a curved surface to reflect illumination light reflected at the second reflecting optical element, and to guide light to an image display element; and
a housing to hold the image display element. The housing has reference guide faces to shift and guide the first and the third reflecting optical elements into a direction where a shape and brightness of an irradiation region to the image display element essentially do not change during positioning of the irradiation region of illumination light to the image display element. The first and the third reflecting optical elements are fixed onto the reference guide faces herein.
An image display optical unit according to a tenth aspect of the invention has:
a first reflecting optical element having a curved surface to reflect illumination light from a light source;
a second reflecting optical element having a curved surface to reflect illumination light reflected at the first reflecting optical element;
a third reflecting optical element having a curved surface to reflect illumination light reflected at the second reflecting optical element, and to guide light to an image display element; and
a housing to hold the image display element. The housing has a reference guide face to shift and guide the second reflecting optical element relative to the first and the third reflecting optical elements into a direction where a shape and brightness of an irradiation region to the image display element essentially do not change during positioning of the irradiation region of illumination light to the image display element. The second reflecting optical element is fixed onto the reference guide face herein.
An image display optical unit according to an eleventh aspect of the invention has:
a first reflecting optical element having a curved surface to reflect illumination light from a light source;
a second reflecting optical element having a curved surface to reflect illumination light reflected at the first reflecting optical element;
a third reflecting optical element having a curved surface to reflect illumination light reflected at the second reflecting optical element, and to guide light to an image display element; and
a housing to hold the image display element. The housing has a reference guide face to parallel shift and guide the second reflecting optical element relative to the first and the third reflecting optical elements into an orthogonal direction to a normal of a reflection face of the second reflecting optical element during positioning of the irradiation region of illumination light to the image display element. The second reflecting optical element is fixed onto the reference guide face herein.